Former Gen. Wesley Clark was speaking before the committee about the federal Renewable Fuel Standard, but Vitter instead decided to press him on work he's done to promote the phone program.

"We’ve had a discussion about another important public policy issue," Vitter told Clark before asking him if the government had paid for his support.

Boxer, the head of the Environment and Public Works Committee, quickly cut the discussion off.

“As chairman of this committee, I give people a lot of lot of leeway. We are not going to attack panelists on other issues. Period, end of quote,” Boxer said. “If you want to do it, have a press conference.”

She later told panelists testifying before the committee that she was “sorry we had a couple of strange personal attacks. I was blindsided by that.”

Vitter has expressed concern that Clark may have accepted money for promoting the federal program, which provides subsidized phone service to poor Americans. The service is sometimes known as the “Obama phone” program, though it began in 1985 and was expanded to include cellphone service during the George W. Bush administration.

“I have not been paid to go down to Louisiana,” said Clark, who ran for president as a Democrat in 2004. “I went down there to talk about Lifeline phones because over 36,000 veterans in the state of Louisiana are dependent on those phones for telephone communication.”

Clark was testifying before the Environment and Public Works Committee on behalf of the ethanol group Growth Energy, where he sits on the board.

Conservative activists have found cases where ineligible applicants received multiple phones under Lifeline, and Vitter maintains that the program has been ridden with fraud.